Chapter 15- Brain and Cranial Nerves Flashcards
brain regions
cerebrum diencephalon mesencephalon cerebrum pons medulla oblongata
meninges: outer layer
dura mater
-forms internal periosteum of skull
no epidura
dura mater partitions
- falx cerebelli: separates right and left cerebellar hemispheres
- falx cerebri: separates right and left cerebral hemispheres
- tentorium cerebelli: separates lobes of cerebrum form cerebellum
2 other layers of meninges
arachnoid mater: -spidery -spreads over brain but doesnt extend into gooves and depressions Pia mater: -inner most -aids in nourishing brain -attached to surface of brain
ventricles
- spaces filled with CSF
- 2 lateral ventricles
- -connected by interventricular foramen to:
- 3rd ventricle: connected by cerebral aqueduct to:
- 4th ventricle: connected to central canal of spinal cord
cerebrospinal fluid functions
- cushions
- transport nutrients, wastes and othe chemicals
- support the brain
cerebrospinal fluid: formation
choroid plexus:
- lobes located in the ventricles
- consists of
- -ependymal cells
- -permeable capillaries
- CSF is taken from blood by ependymal cells and pooled in the ventricles
cerebrospinal fluid: movement
- CSF moves throughout the entire CNS
- originated in ventricles
- through apertures in the 4th ventricles to subarachnoid space
- through central canal
- around subarachnoid space
Cerebrospinal fluid: reabsorbed
in sagittal sinus
- a large venous tube within the dura mater
- extends along the midline of the cerebral hemispheres
- arachnoid extends into sinus through arachnoid granulations
- CSF goes back into the blood
cerebrum: functions
- interpret sensory impulses
- voluntary muscular movements
- memory
- reasoning process
- intelligence and personality
cerebral hemispheres
- 2 hemispheres
- cnnected by corpus callosum
- separated by longitudinal fissure
- possess
- -ridges-gyri
- -grooves=sulci
hemisphere separation
- receives sensory and generates motor information to the OPPOSITE side of the body
- communication between the hemispheres allowed for by corpus callosum
cerebral gray mater
cell somas
- outer regions of cerebral lobes
- centralized in masses called basal nuclei
cerebral white mater
myelinated axons
- commissural fibers
- association fibers
- projection fibers
commissural fibers
connect corresponding gray areas on different hemispheres
association fibers
connect different parts of same hemisphere
projection fibers
connect cerebrum to lower brain areas
cerebral lobes
frontal parietal temporal occipital insula
cerebral lobes division
divided by special sulci
- central sulcus: separates the frontal lobe from the parietal lobe
- lateral sulcus: separates the parietal lobe from the tempoal
- parietal-occipital sulcus: separates the parietal lobe from the occipital
cerebral regions: primary motor cortex
Primary motor cortex
- anterior to central sulcus in frontal lobe
- conscious control of skeletal muscles
- learned motor skills
- speech and eye movements
cerebral regions: primary sensory cortex
- posterior to central sulcus on parietal lobe
- somatic sensory information from touch, pain, pressure
- monitor environment consciously
other sensory cortexs
visual cortex: -occipital lobe -sight -photoreceptors auditory cortex: -temporal lobe -sound olfactory cortex: -temporal lobe -smell gustatory cortex: -insula and frontal lobe -taste
cerebral regions: association areas
- one associated with most large motor or sensory cortexes
- somatic sensory
- somatic motor
- visual
- auditory
- recognize friend on phone (auditory), touch recognition
cerebral regions: high order integrative regions: prefrontal cortex
- meat of brain
- abstract intellectual function
- predictions, problem solving
- emotional context and motivation
- timing and temporal relationships
- removal=pre-frontal lobotomy
- see ppt for picture of area
cerebral regions: high order integrative regions: brocas speech center and general interpretive area
brocas:
-regulates breathing and vocalization
general interpretive area:
-interpretation of both written and verbal language
-sentence structure and word linkage
damage to either results in some sort of aphasia (speech blockage)
hemisphere dominance
higher order integrative regions may be different between hemispheres
-categorical hemisphere
–speech, writing, and general interpretive area
-representational hemisphere
–identification of familiar objects
–touch and spatial analysis
–emotional relevance
right handed people tend to have their categorical hemisphere on left, and vice versa
basal nuclei
- masses of gray matter deep in cerebral hemisphere
- act as relay station for motor impulses starting in cerebral cortex and passing to brain stem and spinal cord
types of basal nuclei
- claustrum
- lentiform nucleus
- caudate nucleus
- amygdaloid nucleus
claustrum
- focuses visual attention
- processes unconscious visual info
lentiform nucleus
controls and adjusts muscle tone
caudate nucleus
- massive head, slender tail
- maintains pattern and rhythm of movement
amygdaloid nucleus
- tip of caudate tail
- part of limbic system
diencephalon
- epithalamus
- -pineal gland: produces melatonin
- posterior pituitary gland
- thalamus
- hypothalamus
thalamus
central to the cerebrum
two major bodies:
-divided by the third ventricle
-connected by a interthalamic adhesion
thalamus: function
part of limbic system: -emotion, memory, learning -conscious awareness of emotion connect basal nuclei and cerebral cortex -to each other -to other parts of the CNS sends sensory information to proper location within cerebrum
hypothalamus; location
below the thalamus
-above and connected to the posterior pituitary gland
hypothalamus: functions
- subconscious control of skeletal muscles
- coordinates autonomic nervous system (sympathetic and parasympathetic)
- the connection between the endocrine and nervous system
- directly produces hormones
- produces behavioral drives (emotions, hunger, thirst)
- regulates body temperature
- controls sleep patterns such as circadian rhythms
mesencephalon
- midbrain
- connects brain stem and spinal cord with higher areas
- act as relay centers
- contain cerebral aqueduct that connects 3rd and 4th ventricles
- parts:
- cerebral peduncles
- red nucleus
- substantia nigra
- corpora quadrigemina
cerebral peduncles
only connecting fibers and no nuclei
- motor fibers connecting the cortex to the spinal cord
- sensory fibers that synapse with the thalamus
red nucleus
- highly vascularized (hence red color)
- connects cerebrum and cerebellum
- controls:
- posture
- reflexes
substantia nigra
- controls and integrates the motor output of the basal nuclei
- produces dopamine (gives it a black color)
- deterioration may lead to parkinson’s disease
- -loss of control of voluntary motor function
corpora quadrigemina
- superior colliculi
- -recieves visual input from thalamus
- inferior colliculi
- -receives auditory input from medulla
pons
- rounded bulge on underside of brain stem
- separates midbrain from medulla
- masses of gray matter and nerve fibers
- relays impulses to and from medulla and cerebrum
- regulates depth of breathing
- rhythm of breathing, wakefullness, sleeping. comatose if damaged
cerebellum
below cerebrum 2 hemispheres: -separated by falx cerebelli -connected by vermis mainly white matter -arbor vitae
cerebellum: function
- integrates sensory information about the position of body parts
- coordinates muscle activities
- maintain posture
- fine tunes voluntary and involuntary movements
medulla oblongata
- from foramen magnum to pons
- a point of connection for several cranial nerves
- oval swelling=olivary nucleus
reflex centers of medulla oblongata
cardiovascular center
-adjusts blood flow and heart rate
respiratory rhythmicity center
-basic pace of respiratory movements
reticular formation (medulla)
- network of nerve fibers associated with islands of gray matter
- interconnects areas with fibers in all major tracts
- regulates motor activities
- -Inc activity=wakefulness
- -dec activity=sleep
limbic system
nuclei and tracts along the border of cerebrum and diencephalon
cerebrum limbic system
- limbic lobe: deep to all other lobes
- hippocampus: nuclei within the lobe
- amydaloid body: basal nucleus
diencephalon limbic system
- thalamus: relay center
- hypothalamus: behavioral drive center
medulla limbic system
reticular formation
-sleep and wakefulness
limbic system function
- establishes emotional states and related behavioral drives
- links intellectual functions of cortex to unconscious functions of lower brain
- facilitates memory storage
cranial nerves
- 12 total
- all originate from brain stem except 1st pair
- cell bodies fro sensory found in ganglia outside brain
- cell bodies for motor found in gray matter
- pass through foramina in skull
cranial nerves general
- may look all disorganized in mammals
- are organized sequentially in fish and cephalochordates
- this is evidenced in a fetus as well
12 cranial nerves
- olfactory
- optic
- oculomotor
- trochlear
- trigeminal
- abducens
- facial
- vestibulocochlear
- glossopharyngeal
- vagus
- accessory
- hypoglossal
I
olfactory
- sensory (means sends signals up)
- smell
- passes through cribiform plate
- only sensation that does not go through the thalamus
II
optic
- sensory
- vision
- pass through the optic foramina
III
oculomotor
- motor (means sends signals down)
- move the majority of eye muscles
IV
- motor
- smallest pair
- superior oblique muscles of eye only
V
trigeminal
- mixed
- larges
- 3 branches
- -eye, tear gland and skin of ant. scalo, forehead and upper eyelid
- -upper teeth, gum, lip and mucous lining of palate and skin of face
- -scalp, skin of jaw, lower teeth, gum and lip; muscles of mastication
VI
abducens
- motor
- form pons
- lateral rectus eye muscles only
VII
facial
- mixed
- sensory: taste receptors on ant. 2/3 of tongue
- motor: to muscles of facial expression; stimulate tear and salivary glands
VIII
vestibulocochlear
- sensory
- auditory nerve from medulla
- 2 parts
- -sensitive to changes in position of head
- -interpreted as hearing
IX
glossopharyngeal
- mixed
- sensory: form lining of pharynx, tonsils and post. 1/3 of tongue
- motor: to wall of pharynx to help swallowing
X
vagus
- mixed
- from medulla to chest and abdomen
- sensory from lining of pharynx, larynx and esophagus and abdomen
- somatic motor: to muscles of larynx–> speech and swallowing
- autonomic motor: to heart, other smooth muscles and glands in visceral organs
XI
-motor
2 branches
-cranial: from medulla to muscles of soft palate, pharynx and larynx
-spinal: sends motor fibers to trapezius and sternocleidomastoid
XII
hypoglossal
- motor
- from medulla to tongue
- for speaking, chewing and swallowing
cranial nerves mnemonic
Name: out on our table top are fruits very green veggies and hamburgers
Composition: some say marry money but my brother says big brains matter more
